stunnel: Home

Stunnel is a proxy designed to add TLS encryption functionality to existing
clients and servers without any changes in the programs' code.
Its architecture is optimized for security,
portability, and scalability (including load-balancing), making it suitable
for large deployments.

Stunnel uses the OpenSSL library for
cryptography, so it supports whatever cryptographic algorithms are compiled
into the library. It can benefit from the
FIPS 140-2
validation of the OpenSSL FIPS Object Module, as long as the building process meets its
Security Policy.
A scanned
FIPS 140-2 Validation Certificate
document is available for download on the NIST web page.
The Windows binary installer is compiled with FIPS 140-2 support.
The FIPS mode of operation is no longer enabled by default since stunnel 5.00.